Olympus Mons, the highest point on Mars, in a computer-generated oblique view made by combining photos obtained by the Viking mission in the 1970s with topographic data gathered by Mars Global Surveyor a quarter century later. The image clearly shows the shield volcano's relative flatness and gently sloping profile, the steep outward-facing cliff at its base (buried in places under lava that has flowed into the surrounding plains), and the complex caldera of intersecting craters at the summit.